Aerodynamic air current diverting apparatus

ABSTRACT

An air current diverting apparatus for a data storage device having a rotating data storage medium in operable relation with an actuator assembly reading data from and writing data to the data storage medium. The air current diverting apparatus has an aerodynamic shroud comprising a base having a first end attachable to the actuator assembly, an upstream surface extending upstream of the actuator assembly, and a downstream surface extending downstream of the actuator assembly and substantially non-parallel to the upstream surface.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of United States ProvisionalApplication Number 60/233,919 filed Sep. 20, 2000 and the benefit ofUnited States Provisional Application Number 60/249,959 filed Nov. 20,2000.

FIELD OF THE INVENTION

[0002] This invention relates generally to the field of data storagedevices, and more particularly but not by way of limitation tocontrolling the aerodynamic excitation imparted to read/write componentsby air currents generated by spinning data storage discs.

BACKGROUND OF THE INVENTION

[0003] Modem data storage devices such as disc drives are commonly usedin a multitude of computer environments to store large amounts of datain a form that is readily available to a user. Generally, a disc drivehas a magnetic disc, or two or more stacked magnetic discs, that arerotated by a motor at high speeds. Each disc has a data storage surfacedivided into a series of generally concentric data tracks where data isstored in the form of magnetic flux transitions.

[0004] A data transfer member such as a magnetic transducer is moved byan actuator to selected positions adjacent the data storage surface tosense the magnetic flux transitions in reading data from the disc, andto transmit electrical signals to induce the magnetic flux transitionsin writing data to the disc. The active elements of the data transfermember are supported by suspension structures extending from theactuator. The active elements are maintained a small distance above thedata storage surface upon an air bearing generated by air currentscaused by the spinning discs.

[0005] A continuing trend in the industry is toward ever-increasing datastorage capacity and processing speed while maintaining or reducing thephysical size of the disc drive. Consequently, the data transfer memberand supporting structures are continually being miniaturized, and datastorage densities are continually being increased. The result is anoverall increased sensitivity to excitation, both from external sourcesand from self-excitation sources, which adversely affect the positioningcontrol systems moving the actuator relative to the spinning discs.

[0006] One source of excitation that can no longer be disregarded comesfrom the air currents moving within the disc stack and impinging on discdrive components. The air current velocity, and hence the associatedforces, increase in relation to the radial distance from the axis ofrotation. Thus, the air currents move faster and are more likelyturbulent at outer portions of the discs. Turbulence can impart adversevibrations, or aerodynamic excitation, to the discs (flutter) and/or tothe actuator, particularly to the suspension members (buffeting).Turbulence can also be created by shedding vortices formed from theactuator wake as the airstream flows past the actuator, and also actingon the disc edges as the air currents are expelled from the disc stack.Further, wake excitation from the actuator increases disc vibration.

[0007] It has been determined that airstream excitation on the datatransfer member can be reduced by an air current diverting apparatuscomprising an air shroud with aerodynamic characteristics. It is to thisimprovement that embodiments of the present invention are directed.

SUMMARY OF THE INVENTION

[0008] Embodiments of the present invention are directed to anaerodynamic air current diverting apparatus for a data storage device,the data storage device having a rotating data storage medium such as adata disc with a recording surface. The data storage device further hasan actuator assembly operably reading data from and writing data to therecording surface, the actuator having, in combination, an actuator armwith a first end adjacent a pivot axis and a second end attached to aflexure member supporting, in turn, a read/write head. The air currentdiverting apparatus has an aerodynamic shroud adaptively diverting aircurrents imparted by the rotating disc around the actuator assembly. Theaerodynamic shroud comprises a base having a first end attachable to theactuator arm and extending substantially parallel to the discterminating in a distal end. The aerodynamic shroud further comprises anupstream surface comprising a first end adjacent the base and a secondend extending upstream of the actuator assembly. The aerodynamic shroudfurther comprises a downstream surface comprising a first end adjacentthe base and a second end extending downstream of the actuator assemblyand substantially non-parallel to the leading surface.

[0009] These and various other features as well as advantages whichcharacterize the present invention will be apparent upon reading of thefollowing detailed description and review of the associated drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010]FIG. 1 is a plan view of a disc drive assembly constructed inaccordance with an embodiment of the present invention.

[0011]FIG. 2 is a diagrammatic cross-sectional view taken along thesection line 2-2 in FIG. 1 at a time when the disc is not spinning andthe read/write head in landed upon the data disc.

[0012]FIG. 3 is a diagrammatic cross-sectional view similar to FIG. 2but at a time when the disc is spinning, imparting an air current to flythe read/write head off the data disc.

[0013] FIGS. 4-8 are diagrammatic cross-sectional views similar to FIG.3 illustrating a number of shrouds constructed in accordance withalternative embodiments of the present invention.

DETAILED DESCRIPTION

[0014] Referring to the drawings in general, and more particularly toFIG. 1, shown therein is a plan representation of a disc drive 100constructed in accordance with embodiments of the present invention. Thedisc drive 100 includes a base deck 102 to which various disc drivecomponents are mounted, and a cover 104 (partially cut-away) whichtogether with the base deck 102 and a perimeter gasket 105 form anenclosure providing a sealed internal environment for the disc drive100. Numerous details of construction are not included in the followingdescription because they are well known to a skilled artisan and areunnecessary for an understanding of the present invention.

[0015] Mounted to the base deck 102 is a motor 106 to which one or morediscs 108 are stacked and secured by a clamp ring 110 for rotation at ahigh speed. Where a plurality of discs 108 are stacked to form a discstack, adjacent discs 108 are typically separated by a disc spacer (notshown). An actuator 112 pivots around a pivot bearing 114 in a planeparallel to the discs 108. The actuator 112 has actuator arms 116 (onlyone shown in FIG. 1) that support load arms 118 (shown in hidden lines)in travel across the discs 108 as the actuator arms 116 move within thespaces between adjacent discs 108. The load arms 118 are flex membersthat support data transfer members, such as read/write heads 120 (shownin hidden lines), with each of the read/write heads 120 adjacent asurface of one of the discs 108 and maintained in a data reading andwriting spatial relationship by a slider (not shown) which operablysupports the read/write head 120 on an air bearing sustained by aircurrents generated by the spinning discs 108.

[0016] Each of the discs 108 has a data storage region comprising a datarecording surface 122 divided into concentric circular data tracks (notshown). Each of the read/write heads 120 operatively interfaces with arespective desired data track to read data from or write data to thedata track. The data recording surface 122 can be bounded inwardly by acircular landing zone 124 where the read/write heads 120 can come torest against the respective discs 108 at times when the discs 108 arenot spinning. Alternatively, the landing zone can be located elsewhereon the disc 108.

[0017] The actuator 112 is positioned by a voice coil motor (VCM) 128comprising an electrical coil 130 and a magnetic circuit source. Themagnetic circuit source conventionally comprises one or more magnetssupported by magnetic poles to complete the magnetic circuit. Whencontrolled current is passed through the actuator coil 130, anelectromagnetic field is set up which interacts with the magneticcircuit causing the actuator coil 130 to move. As the actuator coil 130moves, the actuator 112 pivots around the pivot bearing 114, causing theread/write heads 120 to travel across the discs 108.

[0018] As noted earlier, the motor 106 spins the discs 108 at a highspeed as the read/write head 120 reads data from and writes data to thedata storage surface 122. Kinetic energy transfers from the spinningdiscs 108 to air in the disc stack at the disc/air interface, formingair currents. The disc 108 rotation imparts a rotational force componentto the air currents, and centrifugal force imparts a radial forcecomponent to the air currents. The resulting airstream spirals outwardlyfrom the inner portion of the disc stack, ever-gaining velocity inrelation to the faster linear speed of the discs 108 as the radialdistance from the axis of rotation increases.

[0019] The air currents can adversely effect the reading and writingcapability of the disc drive by aerodynamically exciting the actuatorarm 116, the flexure member 118, and the read/write head 120. Theread/write head 120 typically includes a relatively large air bearingsurface that is lifted by the air currents to fly the read/write head120 extremely close to the disc 108 surface. The flexure member 118imparts an opposing spring force in order to dynamically balance theread/write head 120 at a desired fly height.

[0020] In view of the fact that nominal fly heights are continuallybeing decreased, forces external to this dynamic balance, or “parasiticforces,” are ever-more something that cannot be disregarded. Examples ofsuch parasitic forces include external and internal vibrations, inherentoscillations of disc drive components, and air turbulence.

[0021] Turbulence can be created in different ways, such as the threedimensional wake downstream of the actuator. Compensating for thisimpinging engagement of the flow over the actuator can be complicated bythe acceleration of the actuator assembly into the flow during trackseek operations from an outer track toward an inner track.

[0022] Turning now to FIGS. 1 and 2 which illustrate the read/write head120 parked on the disc 108 surface in the landing zone 124 at a timewhen the disc 108 is not spinning. FIG. 3 is a view similar to FIG. 2but at a time when the disc 108 is moving in direction 132 (shown inphantom lines in FIG. 1) to impart air currents shown diagrammaticallyacting along direction generally in the direction of disc 108 movement,shown by reference arrow 134. The read/write head 120 has an air bearingsurface 136 that is lifted by the air current forces, and which isopposed by the flexure member 118 to dynamically balance the read/writehead 120 at a desired fly height separated from the disc 108 by adesired gap 138. The air bearing surface 136 conventionally hasaerodynamic leading surface features which are omitted in the presentdescription because they are not necessary for an understanding of theembodiments of the present invention.

[0023] The actuator 112 further has an aerodynamic shroud 140 divertingthe air currents around the actuator assembly 112. FIG. 3 shows theshroud 140 has a base portion 142 which is shown having a first endattached to a portion of the actuator arm 116. The base can be adheredor otherwise mechanically fastened to the actuator arm 116.Alternatively, the shroud 140 can be overmolded to the actuator arm 116.In another embodiment the base 142 can be joined to the actuator arm 116in the same process that attaches the flexure member 118 to the actuatorarm 116, such as by riveting or swaging processes.

[0024] The shroud 140 furthermore has an upstream surface 144 having afirst end 145 adjacent to the base 142 and extending upstream of theactuator 112 with respect to the air currents moving in direction 134.The upstream surface 144 extends generally toward the disc 108 surfaceand terminates at a distal end 146 spaced away from the disc 108 suchthat a gap is provided for the air currents to effectively lift theread/write head 120. Otherwise, the air currents are directed around theactuator 112. Preferably, the upstream surface 144 provides anaerodynamic surface for a relatively smooth bending, or redirection, ofthe air currents to minimize the impingement effects on the leading sideof the actuator 112 against the air currents.

[0025] The shroud 140 furthermore has a downstream surface 148 having afirst end 150 adjacent to the base 142 and extending downstream of theactuator 112 with respect to the air currents moving in direction 134.Similar to the upstream surface 144, the downstream surface 148 extendsgenerally toward the disc 108 surface and terminates at a distal end 152spaced away from the disc 108 such that a gap is provided permitting theair currents acting through the air gap 138 to flow past the actuator112. Also similar to the upstream surface 144, the downstream surface148 also provides an aerodynamic surface for the air currents flowingpast the actuator 112.

[0026]FIG. 3 illustrates a preferred embodiment wherein both upstreamand downstream surfaces 144, 148 are angled relative to the air currentsacting in direction 134. These angled upstream and downstream surfaces144, 148 provide the actuator 112 with aerodynamic characteristics thatminimize the impingement effects of the air currents. This embodiment isillustrative, however, and not limiting with regard to the aerodynamicshape of the upstream and downstream surfaces 144, 148. For example,while the embodiment of FIG. 3 illustrates linear surfaces, arcuatesurfaces are contemplated as well within the many embodiments of thepresent invention. Also, although both surfaces 144, 148 are arranged toprovide aerodynamic benefits, it may be beneficial to limit theaerodynamic features to only one or the other of the surfaces 144, 148,as is discussed more below.

[0027] The benefits of the shroud 140 in minimizing aerodynamicexcitation must be balanced against the cost of additional mass on theactuator 112. Accordingly, the preferred embodiment of FIG. 3illustrates a shroud 140 formed of a relatively thin-walled structure inorder to minimize weight. The length of the shroud 140 can also bedetermined according to the needs of a particular application. In FIG.1, for example, the shroud 140 extends from a first end 154 attachmentto the actuator arm 116 to a distal end 156 that is disposed beyond theread/write head 120. Alternatively, in some cases it has been found thatadequate protection is provided by extending the distal end 156 of theshroud 140 only to be disposed adjacent a portion of the flexure member118, or to be disposed adjacent a portion of the actuator arm 116.

[0028] The upstream and downstream surfaces 144, 148 enclose theadjacent portion of the actuator on two sides thereof. In combinationwith the base portion 142, therefore, the adjacent portion of theactuator 112 is enclosed on three sides thereof. When the distal end ofthe base 142 extends beyond the read/write head 120 as in FIG. 1, thenFIG. 4 illustrates the manner in which a distal surface 158 can join theupstream and downstream surfaces 144, 148 to enclose the read/write head120 and the flexure member 118 on at least four sides thereof.Furthermore, any of the embodiments discussed herein can include an aftsurface 159 (shown as phantom in FIG. 3) at the first end 154 joiningthe upstream surface 144 and the downstream surface 148, in order toenclose the read/write head on five sides.

[0029]FIG. 5 is a view similar to FIG. 3 but illustrating an alternativeembodiment of the present invention wherein a shroud 240 similarly hasupstream and downstream aerodynamic surfaces 144, 148 extending from acentral supporting base 140. Additionally, an upstream enclosure surface160 extends from the upstream surface distal end 146 and substantiallyparallel to the data disc 108. The upstream enclosure surface 160 guidesthe air currents entering the gap 138, further diverting them from theactuator 112. Similarly, the shroud 240 has a downstream enclosuresurface 162 extending from the downstream surface distal end 152 andextending substantially parallel to the disc 108. The downstreamenclosure surface 162 guides the air currents out of the gap 138 andpast the actuator 112.

[0030]FIG. 6 illustrates a shroud 340 constructed in accordance with analternative embodiment of the present invention wherein a substantiallysolid cross-section member is provided. It has been determined thatequivalent performance can be achieved by using a relatively less-densematerial to provide the aerodynamic surfaces previously described.Alternatively, FIG. 7 illustrates a shroud 440 similarly constructed ofa substantially solid cross-section but having longitudinal openings 164to reduce the weight.

[0031] As discussed previously, the many embodiments illustrated anddescribed hereinabove contemplate an aerodynamic shroud enclosing adesired portion of the actuator 112. Preferably, both the upstream anddownstream surfaces 144, 148 of the shroud have aerodynamic responsecharacteristics relative to the air currents moving in direction 134. Ithas been determined, however, that even if only one of the surfaces ischaracteristically aerodynamic then excitation effects are greatlyreduced in comparison to no shroud and/or shrouds constructed inaccordance with the present state of the art. For example, FIGS. 8 and 9illustrate shrouds 540, 640, respectively, having only one aerodynamicsurface. The downstream surface 148 of shroud 540 and the upstreamsurface 144 of shroud 640 provide substantially improved resistance toaerodynamic excitation, albeit less than the preferred embodiment, suchthat they are within the scope of the embodiments contemplated by thepresent invention. In all cases of the many embodiments of the presentinvention it will be noted from the illustrations and descriptionhereinabove that in order to achieve the aerodynamic characteristicsnecessary to sufficiently reduce aerodynamic excitation, the upstreamsurface 144 is disposed relative to the downstream surface 148 such thatthey are non-parallel with regard to each other.

[0032] Although the illustrative embodiments shown illustrate a shroudconstructed of a material having a substantially constant wallthickness, alternatively the material can be tapered to further providean aerodynamic characteristic. The aerodynamic features canalternatively be machined as part of or into the actuator to eliminatethe process step of attaching a separate component part. The shroud canfurthermore be tapered from the first end 154 to the second end 156where the read/write head 120 is narrower than the supporting portion ofthe actuator arm 116, so as to envelope the read/write head 120 asclosely as possible.

[0033] In summary, a shroud (such as 140) is an integral part of anactuator (such as 112) in operable relation with a data storage medium(such as disc 108) in a data storage device (such as 100) to reduceparasitic forces created by the air currents created by the spinningdiscs. The shroud has aerodynamic features (such as 144, 148) that bendthe air currents around the actuator to reduce the impinging effects ofthe air currents against the actuator. The shroud furthermore shieldsthe actuator from the three dimensional wake on the downstream side ofthe actuator.

[0034] It is to be understood that even though numerous characteristicsand advantages of various embodiments of the present invention have beenset forth in the foregoing description, together with details of thestructure and function of various embodiments of the invention, thisdisclosure is illustrative only, and changes may be made in detail,especially in matters of structure and arrangement of parts within theprinciples of the present invention to the full extent indicated by thebroad general meaning of the terms in which the appended claims areexpressed. For example, the size and placement of the air currentdiverting apparatus may vary depending on the particular applicationwhile maintaining substantially the same functionality without departingfrom the scope and spirit of the present invention. In addition,although the preferred embodiment described herein is directed to an airdiverting apparatus for a disc drive assembly, it will be appreciated bythose skilled in the art that the teachings of the present invention canbe applied to other systems, like data storage test or certificationsystems or optical data storage systems, without departing from thescope and spirit of the present invention.

What is claimed is:
 1. An air current diverting apparatus for a datastorage device, the data storage device having a rotating disc with arecording surface and an actuator assembly operably reading data fromand writing data to the recording surface, the actuator having, incombination, an actuator arm with a first end adjacent a pivot axis anda second end attached to a flexure member supporting, in turn, aread/write head; the apparatus comprising: an aerodynamic shroudadaptively diverting air currents imparted by the rotating disc aroundthe actuator assembly, the aerodynamic shroud comprising: a base havinga first end attachable to the actuator arm and extending substantiallyparallel to the disc terminating in a distal end; an upstream surfacecomprising a first end adjacent the base and a second end extendingupstream of the actuator assembly; and a downstream surface comprising afirst end adjacent the base and a second end extending downstream of theactuator assembly and substantially non-parallel to the leading surface.2. The apparatus of claim 1 wherein the base distal end is disposedadjacent a portion of the actuator arm.
 3. The apparatus of claim 1wherein the base distal end is disposed adjacent a portion of theflexure member.
 4. The apparatus of claim 1 wherein the base distal endis disposed beyond the read/write head.
 5. The apparatus of claim 4further comprising a distal surface joining the upstream and downstreamsurfaces enclosing the read/write head on four sides.
 6. The apparatusof claim 1 further comprising an upstream enclosure surface extendingfrom the upstream surface second end and substantially parallel to thedata disc.
 7. The apparatus of claim 1 further comprising a downstreamenclosure surface extending from the downstream surface second end andsubstantially parallel to the data disc.
 8. The apparatus of claim 1wherein the data storage apparatus comprises a disc drive assembly.
 9. Adisc drive, comprising: a base deck; a spindle motor mounted to the basedeck and having a central axis; a data disc mounted to the spindle motorfor rotation about the central axis, the disc having a recordingsurface; and an actuator assembly having an actuator arm with a firstend adjacent a pivot axis and a second end attached to a flexure membersupporting, in turn, a read/write head, the actuator assembly comprisingan aerodynamic shroud diverting air currents from the actuator assembly,the aerodynamic shroud comprising: a base having a first end attachableto the actuator arm and extending substantially parallel to the discterminating in a distal end; an upstream surface comprising a first endadjacent the base and a second end extending upstream of the actuatorassembly; and a downstream surface comprising a first end adjacent thebase and a second end extending downstream of the actuator assembly andsubstantially nonparallel to the leading surface.
 10. The disc drive ofclaim 9 wherein the base distal end is disposed adjacent a portion ofthe actuator arm.
 11. The disc drive of claim 9 wherein the base distalend is disposed adjacent a portion of the flexure member.
 12. The discdrive of claim 9 wherein the base distal end is disposed beyond theread/write head.
 13. The disc drive of claim 12 further comprising adistal surface joining the upstream and downstream surfaces enclosingthe read/write head on at least three sides.
 14. The disc drive of claim9 further comprising an upstream enclosure surface extending from theupstream surface second end and substantially parallel to the data disc.15. The disc drive of claim 9 further comprising a downstream enclosuresurface extending from the downstream surface second end andsubstantially parallel to the data disc.
 16. A disc drive assembly,comprising: a read/write head assembly operably moveable in a datareading and writing relationship with a data storage disc; and means forreducing turbulent air currents generated from the spinning data storagedisc and acting on the read/write head assembly.
 17. The disc driveassembly of claim 16 wherein the means for reducing turbulent aircurrents comprises a shroud moveable with the read/write head assemblyand having non-parallel leading and trailing edges enclosing theread/write head assembly on at least two sides.
 18. The disc driveassembly of claim 17 wherein read/write head assembly comprises anactuator arm having a first end adjacent a pivot axis and a second endsupporting a flexure member supporting, in turn, a read/write head,wherein the shroud encloses a portion of the actuator on at least twosides.
 19. The disc drive assembly of claim 18 wherein the shroudencloses a portion of the flexure member on at least two sides.
 20. Thedisc drive assembly of claim 18 wherein the shroud encloses theread/write head on at least two sides.
 21. The disc drive assembly ofclaim 20 further comprising a distal surface joining the upstream anddownstream surfaces enclosing the read/write head on at least threesides.
 22. The disc drive assembly of claim 18 further comprising anupstream enclosure surface extending from the upstream surface secondend and substantially parallel to the data disc.
 23. The disc driveassembly of claim 18 further comprising a downstream enclosure surfaceextending from the downstream surface second end and substantiallyparallel to the data disc.
 24. The apparatus of claim 5 furthercomprising an aft surface joining the upstream surface and downstreamsurface to enclose the read on five sides.